This disclosure relates in general to data communications and, but not by way of limitation, to communication using a compliant medium.
Electronic communication takes place wirelessly using radio frequencies, optically using light and with wires using electron flow. Often these communication mechanisms are not practical in certain applications. For example, wires are difficult to string along pipelines and down a bore hole. Equipment needs to communicate information despite limitations on available communications medium.
There are systems for down hole communication using pressure in a hydraulic line. The pressure in the hydraulic line is modulated by the pump with data to communicate with sub-surface devices that have no other communication medium available. Over time, the pressure can be increased and decreased to send information. These systems only communicate away from the pump.
Other systems use acoustic waves to communicate. An acoustic wave is produced and a gate may be inserted and removed to modulate the reflection of the acoustic wave. These systems require a generally direct path from the acoustic source back to the sensor registering the reflection. Heavily damped systems are not appropriate candidates for these systems.
On occasion, drillstrings can become snagged somewhere down hole. To determine the location of the snag, tension is put on the drillstring. A point of the drillstring is marked. Tension is increased and the distance the mark moves is measured. The distance and the differential in tension can be used to determine how far down the drillstring the snag occurs.